SimMechanics Release Notes

R2014b

Constraint force and torque sensing in Constraint blocks

Compute and output the forces and torques that enable a Constraint
block to enforce its kinematic constraint. The blocks output one or
more physical signals with the variables that you select. These variables
can include the constraint force and torque vectors and their signed
magnitudes. The blocks resolve the vector quantities in the resolution
frame that you specify.

The new blocks with constraint force and torque sensing are Angle Constraint and Distance
Constraint. These blocks expand the list of blocks with constraint
force and torque sensing. You can also sense constraint forces and
torques through Joint blocks.

Solid 3-D visualization in Solid block dialog box

Visualize the solid you are modeling directly in the Solid block dialog box. The updated block includes
a collapsible visualization pane that shows the current state of your
3-D solid. You can use this pane to check the geometry and color of
individual solids before updating or simulating the model.

The visualization pane includes a toolstrip for controlling
the solid view. The toolstrip, which provides many of the Mechanics
Explorer toolstrip buttons, enables you to rotate, pan, and zoom a
solid, to select a standard view point, and to visualize the solid
reference frame.

Rotation matrix parameterization in Rigid Transform and Joint
blocks

Specify a frame rotation using a 3-D rotation matrix. The new
parameterization is available in two block types, Rigid
Transform and joint blocks with spherical joint primitives.
Use this parameterization in the Rigid Transform block to specify
a fixed rotation or in a joint block to specify the position state
target of a spherical joint primitive. The joint blocks with the new
parameterization are:

R2014a

STEP file import

Load solid geometry directly from a STEP file. This file type
enables SimMechanics™ to automatically compute inertia from
solid geometry, an advantage over STL files. You can generate the
STEP file that you want to load externally, e.g., using a CAD platform.

Total and constraint force and torque calculation in joint
blocks

Sense the total and constraint forces and torques acting at
whole joints. Joint block dialog boxes provide a new expandable parameter
list, Composite Force/Torque Sensing, in which
you can select the whole-joint variables to sense. Select a variable
to calculate its time-dependent values during simulation and deliver
them through a physical signal output port. Variables that you can
sense include:

Total Force/Torque — Net sum of forces and
torques acting at the joint. These variables include contributions
from actuation, internal mechanics, and constraint forces and torques.

Constraint Force/Torque — Forces and torques
acting orthogonally to the joint degrees of freedom. In a Revolute
Joint block, which provides a single rotational degree of freedom
about the Z axis, the constraint forces act along all the Cartesian
axes (X, Y, and Z), while the constraint torques act about the X and
Y axes.

Time-varying gravity option in Mechanism Configuration block

Specify the gravitational acceleration vector as a function
of time, using the Mechanism
Configuration block. To support this task, the Uniform
Gravity parameter in the block dialog box now provides
a Time-Varying option. Select that option
to expose a physical signal port to which you can connect a time-varying
gravity physical signal. The gravitational acceleration vector is
strictly uniform in space. It does not vary with position.

Gravitational Field block

Model the gravitational pull of a point mass on every rigid
body in a mechanism. The Gravitational
Field block exerts a force that varies with mass and
distance according to Newton's law of universal gravitation.
Applications include large-scale orbital systems in which gravity
changes due to varying distances play an important role—e.g.,
a solar system model for spacecraft trajectory planning. The block
is in the Forces and Torques library.

Animation at arbitrary speed in Mechanics Explorer

Change the base playback speed of a SimMechanics animation
by an arbitrary factor. This speed corresponds to the 1x animation
slider setting in Mechanics Explorer. It equals the number of seconds
in simulation time that play in one second of animation playback time.

You can specify the base playback speed as a numerical input
in Mechanics Explorer. This parameter appears in Tools > Animation Settings. Change its value to better visualize motion at extreme
time scales.

The new parameter is relevant, for example, in a solar system
model. At the default value of the base playback speed, planet motion
is exceedingly slow. Due to the time scale of such a model, moving
the playback speed slider to its maximum value of 256× does not
suffice. Planet motion remains nearly imperceptible.

To visualize one Earth revolution in minutes or seconds, you
must increase the playback speed by a very large factor. This factor
might be seven orders of magnitude larger than the default value—larger
than the playback speed slider allows. You specify such a large playback
speed using the new base playback speed parameter.

Consider a model of the solar system. You can play animation
at a rate of one Earth revolution per second. To play animation at
this rate, you specify a base playback speed of

365dayssecond·24hoursday·60minuteshour·60secondsminute=3.15e7.

You can then use the playback speed slider to fine-tune
the playback speed. The slider multiples the base playback speed by
factors of two between a minimum of 1/256 and a maximum of 256.

Internal Force block for modeling action and reaction forces

General force acting between two rigid body frames along the
line connecting their origins

Published XML Schema for model import, enabling users to import
mechanical models from external applications such as CAD systems

SimMechanics now provides an XML schema that you can
use to generate SimMechanics Import XML files. Use the schema
in conjunction with the API of an external application, such as a
CAD platform, to generate a valid SimMechanics Import XML file
for a multibody model. Then, import this file to automatically generate
an equivalent model in SimMechanics Second Generation format.

Higher Gravity Precision

The gravity vector in the Mechanics Configuration block now
has a precision of six significant digits (-9.80665 m/s^2).
Older models with a Mechanism Configuration block retain the older
precision level of three significant figures. To apply the higher
precision level in these models, you can manually update the gravity
vector.

Second Generation technology now supporting C-code generation
with Simulink Coder

SimMechanics Second Generation now supports
code generation with Simulink® Coder.
Generate C code from a SimMechanics model,
and use the code for applications like hardware-in-the-loop (HIL)
testing and rapid prototyping.

SimMechanics Second Generation does
not support run-time parameters. Model parameters are fixed during
code generation, and are not available for edit outside SimMechanics.
To update model parameters, you must edit them in SimMechanics and
then regenerate the C code for your model.

Solid of revolution geometry in Solid block

The Solid block
adds a Revolution geometry. The geometry represents
solids that have a constant cross-section about an axis of revolution.
Examples include cones, domes, and toroids. Revolutions can be full
or partial.

Changes to inertia specification

The form of the Products of Inertia input
vector has changed in Solid and Inertia blocks.
The new input vector has the form [Iyz,
Izx, Ixy].
The vector elements correspond to the inertia matrix off-diagonal
elements:

R2012a

SimMechanics Version 4.0 Software and Second Generation
Technology

SimMechanics Version 4.0 introduces Second Generation
technology to model, simulate, and analyze two- and three-dimensional
multi-body mechanical systems. Second Generation technology provides
a more intuitive and powerful block diagram language that lets you
easily create reusable parts and libraries. It also adds advanced
three-dimensional visualization and animation support.

Version 4.0 provides full support for both First Generation
and Second Generation functionality, including block sets and tools.
With Version 4.0, you have the option to create and simulate a mechanical
model using First or Second Generation technology. Version 4.0 software
gives you the two full block libraries, labeled First Generation and
Second Generation.

Note:
The term generation — e.g. "Second Generation"
— refers to the SimMechanics technology
used. A SimMechanics version may
contain one or both generations.

SimMechanics First and Second Generation
Technologies

SimMechanics Second Generation technology
is a comprehensive advancement of SimMechanics First
Generation technology. To ease the transition from First Generation
to Second Generation technology, and to support existing First Generation
users, SimMechanics Version 4.0 fully supports both First
Generation and Second Generation features.

This table summarizes First Generation and Second Generation
technologies in their native SimMechanics versions.

Technology

Description

Block Library

SimMechanics First Generation

Encompasses the complete SimMechanics behavior through
Version 3.2.3 (R2011b). First Generation features are designated by
the First Generation library in both the Simulink Library
Browser and the Help Browser windows.

To access the block library, at the command line, type mechlibmechlib.

SimMechanics Second Generation

Encompasses the new SimMechanics behavior in Version
4.0 (R2012a). Second Generation features are designated by the Second
Generation library in both the Simulink Library
Browser and the Help Browser windows.

Compatibility Considerations

First- and second-generation blocks are based on different languages.
To interconnect the two block types, you must use Simulink-PS
Converter and PS-Simulink
Converter blocks. You can find the converter blocks
in the Simscape Utilities library.

Improvements in SimMechanics Second
Generation Technology

The following functionality has been added or improved for SimMechanics Second
Generation:

Multibody modeling paradigm centered on frames, including:

Ports and nodes map that directly to frames

Frames that are strictly locally-defined

Mechanics Explorer visualization utility

Visualize 3–D models

Explore model using tree browser and visualization
panes

Enhanced animation support

Control animation speed

Replay animation without rerunning simulation

Inertia calculation and joint state targets

Automatically calculate inertia from geometry

Specify joint state target values and priority settings

Improved integration with Simscape™.

Includes support for physical signals and units.

Common Functionality in SimMechanics First
and Second Generation Technologies

The following functionality is present in both SimMechanics First
and Second Generations:

Rigid body specification

Joint specification

Constraint specification

Force and torque inputs

Linearization of mechanical models

Trimming mode of analysis

Motion outputs

Functionality Found Only in SimMechanics First
Generation Technology

The following functionality is present only in SimMechanics First
Generation:

Code generation support

Model reference accelerator mode is absent in the SimMechanics Second
Generation sub-library.

CAD import support

Motion input in Joint Blocks

Force outputs in Joints and Constraints blocks

Missing Constraints blocks:

point-curve, gear, velocity,
and projection constraints are not included in
the SimMechanics Second Generation sub-library.

Missing Force Outputs

Applied and reaction force outputs for joints are
not available.

Missing Joints

Screw and massless
connector joint blocks are not included in the SimMechanics Second
Generation sub-library.

Variable gravity and mass distribution

Visualization features

Model reference normal mode is not included in SimMechanics Second
Generation technology.

This release introduces "What's This?" context-sensitive
help for parameters that appear in the Import Physical Modeling XML
dialog opened by entering mech_import with
no arguments at the command line. This feature provides quick access
to a detailed description of the parameters, saving you the time it
would take to find the information in the Help browser.

To use the "What's This?" help, do the following:

Place your cursor over the label of a parameter.

Right-click. A What's This? context
menu appears.

For example, the following figure shows the What's
This? context menu appearing after a right-click on
the Start time parameter in the Solver pane.

Click What's This? A context-sensitive
help window appears showing a description of the parameter.

The Connection
Port block has been removed from the block libraries
of all add-on products dependent on Simscape software. When using
these dependent add-on products, look for the Connection Port block
in the Simscape Utilities library.

The Connection Port block help for these add-on products now
directs you to the Simscape block reference.

Reference Coordinate Systems in Imported Physical Modeling
XML

With the SimMechanics Link utility,
you can export reference coordinate systems that you insert into CAD
assemblies. (This feature is not supported on all CAD platforms.)
From the exported Physical Modeling XML, you can generate a SimMechanics model
with extra Body coordinate systems corresponding to the assembly reference
coordinate systems and not associated with CAD constraints and automatically
generated Joints.

Using the new GearAssembly.xml file, the new
demo pagenew
demo page explains how you can use reference coordinate systems
to help you manually add a Constraint block to a model after import.

Pro/ENGINEER CAD Translation Case Study

The CAD translation chapter now contains a case
studycase study demonstrating
assembly export and re-export, along with model import and update.
The study uses SimMechanics and SimMechanics Link software,
together with Pro/ENGINEER®, and models a double pendulum, subsequently
modified to a triple pendulum. The study illustrates how you can update
an existing generated CAD-based model with successive changes to the
original CAD assembly.

Compatibility Considerations

The old SimMechanics visualization allowed you to save
visualization settings to a MAT-file associated with a SimMechanics model.

When you open such a model in the new version, the model will
attempt to load the MAT-file, as before, and map the old visualization
options to the new options as closely as possible. This is a one-time
conversion. The MAT-file has to be on the MATLAB® path so it can
be found when you open the model.

To save these converted visualization settings:

You must open the visualization window and save these
settings to the model.

To compress a recorded animation of a simulation, you need the
Indeo 5 codec. This codec might not be available on the 32-bit Windows Vista™ operating
system and the 64-bit Windows® XP and Windows Vista operating
systems. If you require compression and the codec is not found, the
animation AVI file is still saved, but without compression. A warning
appears.

New Visualization Window Status Bar Not Available on Intel Mac Operating
System

The status bar of the new visualization window, below the machine
display, does not appear at all on the Intel® Mac operating
system. On other operating systems, the status bar shows simulation
time, as well as Body block and coordinate system names.

New Visualization Not Supported on Solaris 64 UNIX Operating
System

The new visualization and animation interface is not available
on the Solaris 64 UNIX operating system. SimMechanics software
automatically reverts to the old visualization interface.

New SimMechanics Link Utility

The new SimMechanics Link utility provides a bridge from
third-party mechanical design and modeling applications to the system
and control design features of MATLAB and Simulink. It connects
computer-aided design (CAD) platforms to mechanical modeling with SimMechanics software
by enabling export of CAD assemblies into the Physical Modeling XML
format that allows for automatic generation of SimMechanics models.

Refer to the SimMechanics Link documentation for
more information. The SimMechanics Link utility requires MATLAB,
but not Simulink, Simscape, or SimMechanics.

Compatibility Considerations

Physical Modeling XML files generated by the old CAD-to-SimMechanics translators
remain compatible with mech_import. Using this
command, you can still import old XML files to generate SimMechanics models.
Because these models have no associated exported STL body geometry
files, they will visualize using the standard (noncustom) body shapes.

The updating feature of mech_import works
only with Physical Modeling XML files generated by exporting from
the SimMechanics Link utility. This feature does not work with
Physical Modeling XML files generated from the old CAD-to-SimMechanics translators.

Caution
Do not attempt to use the import_physmod command
in older SimMechanics versions with Physical Modeling XML files
generated by the new SimMechanics Link exporter.

BodyBuilder for Creating STL Body Geometry Files

In addition to generating STL body geometry files automatically
from a CAD assembly, you can also create STL files by hand or by using
a body geometry editor. BodyBuilder is an application based on MATLAB that
provides a graphical means to create STL files for use in SimMechanics body
visualization. You can obtain BodyBuilder from MATLAB
Central.

Pro/ENGINEER CAD Translation Case Study

A new CAD translation case study, available
from MATLAB Central, demonstrates assembly export and re-export,
along with SimMechanics model import and update, using SimMechanics and SimMechanics Link software.
The study is based on Pro/ENGINEER and models a double pendulum,
subsequently modified to a triple pendulum. The study illustrates
how you can update an existing generated CAD-based model with successive
changes to the original CAD assembly.

Physical Modeling of Mechanical Friction

A recent MATLAB
Digest article explains how to simulate mechanical friction
with Simulink, SimDriveline™, and SimMechanics models.
A set of models accompanies the article in a compressed
zip archive available from MATLAB Central.

R2008a

"What's This?" Context-Sensitive Help
Available for Simulink Configuration Parameters Dialog

R2008a introduces "What's This?" context-sensitive
help for parameters that appear in the Simulink Configuration
Parameters dialog. This feature provides quick access to a detailed
description of the parameters, saving you the time it would take to
find the information in the Help browser.

To use the "What's This?" help, do the following:

Place your cursor over the label of a parameter.

Right-click. A What's This? context
menu appears.

For example, the following figure shows the What's
This? context menu appearing after a right-click on
the Start time parameter in the Solver pane.

Click What's This? A context-sensitive
help window appears showing a description of the parameter.

R2007b

Interfacing with One-Dimensional Simscape Domains

The Prismatic-Translational
Interface and Revolute-Rotational Interface blocks
of the new Interface Elements library allow you to connect a SimMechanics Prismatic
or Revolute joint primitive to a Physical Networks line connected
to Simscape blocks. The Prismatic-Translational Interface and
Revolute-Rotational Interface blocks transfer mechanical velocities
and forces/torques as Physical Networks cross- and through-variables,
respectively, without energy loss, along or around axes that you can
define.

Several new demos illustrate the use of the Interface Elements
blocks. See New
Demos following.

SimMechanics State Names Now Available to Simulink and
Real-Time Workshop

You can access the names of the mechanical states of your SimMechanics models
through the mech_stateVectorMgr command. The
names of these states and the SimMechanics blocks that define
them are now available to Simulink and appear in the outputs
of model simulations. They also appear in simulations based on code
generated with Real-Time Workshop.

Controlling Redundant Constraint Analysis with New Tolerance
Setting

You can now adjust the sensitivity of the SimMechanics redundant
constraint analysis in the Constraints tab of
the Machine
Environment block, which allows you to choose between
automatic constraint redundancy analysis or specifying a constraint
redundancy tolerance explicitly.

Certain mechanical configurations are sensitive to the constraint
redundancy tolerance and can spuriously lose or gain degrees of freedom
if this tolerance is adjusted incorrectly.

Code Generation Documentation Consolidated to Simscape User's
Guide

Documentation of code generation features common to all Physical
Modeling add-on products based on Simscape software has been
consolidated to the Simscape User's
Guide. The SimMechanics User's Guide continues
to document uniquely SimMechanics features related to code generation.

R2007a

SimMechanics Software Now Requires Simscape Product

SimMechanics software now depends on and requires Simscape software,
the foundation for Physical Modeling products. Simscape software
includes common Physical Modeling utilities and block libraries.

Sharing Models Using Simscape Editing Modes

SimMechanics software now features a selection of two Simscape editing
modes that allow full or restricted editing of models.

The Restricted mode requires SimMechanics product
to be installed, but does not require a license. It allows you to
change a limited set of model parameters, but not the blocks or connections,
in a SimMechanics model.

The Full mode requires both Simscape and SimMechanics products
to be installed. It allows you to change anything in a SimMechanics model.

Block Library Links Must Be Resolved

All SimMechanics blocks in your models must now have resolved
block library links. You can neither disable nor break these library
links. This is a global Simscape requirement. Consult the Simscape documentation for
further details.

Compatibility Considerations

If you have an existing SimMechanics model with disabled
or broken links from SimMechanics blocks to the SimMechanics block
library, you must restore all the broken block library links for your
model to be valid.

If you have disabled or broken the SimMechanics library
link for blocks that you have customized and want to keep these modified
blocks in your model, you must move these modified blocks to your
own custom library or libraries, then copy the block instances that
you need to your model.

You must still restore the block link to its parent library,
whether that parent is the SimMechanics block library or your
own.

Two Blocks Now with Tunable Parameters

These SimMechanics parameters are now tunable from their
respective block dialogs:

R2006b

Computer-Aided Design Translator for Pro/ENGINEER Available
via the Web

A new computer-aided design (CAD) Pro/ENGINEER-to-SimMechanics translator
is available. You install and use this translator with Pro/ENGINEER.
It is independent of MATLAB.

The translator converts a Pro/ENGINEER CAD machine assembly
into an XML file in the Physical Modeling format. The XML file represents
the assembly in a form that you can use to generate a SimMechanics block
diagram model dynamically equivalent to the original CAD assembly.
To generate models, use the import_physmod command.

Installing the Pro/ENGINEER-to-SimMechanicsTranslator

Obtain and use the installer executable by locating and downloading
its archive at www.mathworks.com/products/simmechanics/.
A README page is provided that describes installation and configuration
details.

Translator Documentation

Help files accompany the Pro/ENGINEER-to-SimMechanics translator.
They include two HTML pages and a PDF book. These files are independent
of the MATLAB help system.

Translator Examples

Some examples of Pro/ENGINEER CAD assemblies are included
with the Pro/ENGINEER-to-SimMechanics translator.

One of the examples is a robot arm assembly. The corresponding
XML file in Physical Modeling format, robot.xml,
is located in the toolbox/physmod/mech/mechdemos/ folder,
relative to your MATLAB root.

Compatibility Considerations

Versions of Pro/ENGINEER compatible with the Pro/ENGINEER-to-SimMechanics translator
are listed at the MathWorks Web site. The translator
is available only for the Microsoft Windows (32-bit) operating
system.

SolidWorks-to-SimMechanics Translator Now Available
Only via the Web

The existing SolidWorks®-to-SimMechanics translator
for the SolidWorks CAD platform continues to be available via
the Web, at www.mathworks.com/products/simmechanics/.
However, it no longer ships with the SimMechanics product.

Compatibility Considerations

Versions of SolidWorks compatible with the SolidWorks-to-SimMechanics translator
are listed at the MathWorks Web site.

The SolidWorks CAD platform and the SolidWorks-to-SimMechanics translator
are available only for the Microsoft Windows (32-bit) operating
system.

New Demo

This version of SimMechanics software includes one new
demo model, mech_brownian_oscmech_brownian_osc,
a stochastic linear harmonic oscillator based on micro- and biomechanics.

Modeling Flexible Bodies with SimMechanics Software

A new MATLAB
Digest article and related technical paper explain how to
simulate flexible bodies with SimMechanics models and third-party
finite element analysis applications. A set of models accompanies
the technical paper in a compressed
zip archive available from MATLAB Central.

Mates in a CAD assembly (restrictions on the free
motion of CAD parts) are now translated into Joint blocks that reflect
a particular combination of joint primitives, such as Prismatic, Revolute,
Spherical, Bushing, etc. Previously, all degrees of freedom in a CAD
assembly were translated into appropriately configured Custom Joint
blocks. Rigid connections between parts continue to be translated
into Welds.

Blocks in SimMechanics models generated from
Physical Modeling XML files are now, by default, labeled with shorter
names. You can change the naming convention in the import_physmod command
options.

R14SP3

New Shared Environment Block

The new Shared
Environment block allows you to link two separate SimMechanics block
diagrams with a nonphysical connection. The block enforces the same
machine environment settings on both machines but adds no mechanical
components (bodies or degrees of freedom) to either. Two machines
so connected require exactly one Machine
Environment block, rather than two.

Normalizing Rotations

The Body dialog
accepts various rotational forms (Euler angles, rotation matrix, quaternion).
The Body block now interprets these rotational forms in a slightly
different way, so that the standard normalization conditions on rotation
matrices and quaternions are consistently enforced. As a result, you
might now see slightly different simulation results from earlier versions.

New State Vector Commands

Four new SimMechanics commands allow you to manipulate
the mechanical states of your models. See the command references for
more.

New import_physmod Dialog

The import_physmod command generates SimMechanics models
from Physical Modeling XML files. In addition to importing Physical
Modeling XML through the command line, you can now set up the command
through a dialog.

Documentation Enhancements

The computer-aided design (CAD) documentation (also
available as a separate book) has been significantly revised. See
the CAD
chapter.

A new chapter of case studies, based on the Stewart
platform, has been added. The studies apply advanced methods and tasks
to this system. SimMechanics software includes a related set
of demo model and library files.